SECTION A — MCQs
1.
Which statement best explains why the cell is called the basic structural and functional unit of life?
A. Every cell has a cell wall.
B. All organisms are made of cells, and cells perform essential life functions.
C. Every cell contains chloroplasts.
D. Cells can survive independently in all organisms.
2.
Robert Hooke observed small box-like compartments while examining:
A. Onion peel
B. Blood
C. Cork
D. Pond water
3.
The approximate limit of resolution of the unaided human eye given in the chapter is:
A. 1 mm
B. 0.1 mm
C. 0.01 mm
D. 10 nm
4.
A microscope has a 10X eyepiece and a 40X objective lens. What is its total magnification?
A. 40X
B. 50X
C. 400X
D. 4000X
5.
Which property determines how clearly two closely spaced objects can be distinguished?
A. Magnification
B. Resolution
C. Contrast
D. Illumination
6.
Why is an electron microscope useful for studying cells?
A. It uses visible light to observe whole organisms.
B. It can reveal very fine structures at the nanometre scale.
C. It makes cells grow faster.
D. It measures cell weight.
7.
A potato piece placed in plain water swells mainly because:
A. Salt enters the cells.
B. Water enters the cells by osmosis.
C. Sugar enters the cells by diffusion.
D. The cell wall dissolves.
8.
Osmosis involves the movement of:
A. Solute from higher to lower concentration
B. Water through a selectively permeable membrane
C. Proteins through the cell wall
D. DNA through the nuclear membrane
9.
Which statement correctly distinguishes diffusion from osmosis?
A. Diffusion involves only water.
B. Osmosis involves the movement of water through a selectively permeable membrane.
C. Diffusion always requires a selectively permeable membrane.
D. Osmosis occurs only in animal cells.
10.
A solution having the same solute concentration outside and inside a cell is:
A. Hypertonic
B. Hypotonic
C. Isotonic
D. Concentrated
11.
A cell placed in a medium with a higher solute concentration outside the cell is in a:
A. Hypotonic medium
B. Hypertonic medium
C. Isotonic medium
D. Neutral medium
12.
The fluid-mosaic model describes the structure of the:
A. Cell wall
B. Cell membrane
C. Nucleus
D. Cell sap
13.
In the lipid bilayer of the cell membrane:
A. Water-attracting heads face inward.
B. Water-repelling tails face outward.
C. Water-attracting heads face outward and water-repelling tails face inward.
D. Proteins form the entire membrane.
14.
Which structure is present outside the cell membrane in plant, fungal and bacterial cells?
A. Nucleus
B. Cell wall
C. Golgi apparatus
D. Lysosome
15.
The major component of the plant cell wall mentioned in the chapter is:
A. Protein
B. Lipid
C. Cellulose
D. DNA
16.
Which feature distinguishes a typical prokaryotic cell from a eukaryotic cell?
A. Presence of ribosomes
B. Presence of cytoplasm
C. Absence of a well-defined membrane-bound nucleus
D. Presence of a cell membrane
17.
The genetic material of a prokaryotic cell is located in the:
A. Nucleolus
B. Nucleoid
C. Golgi apparatus
D. Vacuole
18.
Which combination is characteristic of eukaryotic cells?
A. Nucleoid and no membrane-bound organelles
B. Well-defined nucleus and membrane-bound organelles
C. No cytoplasm and a cell wall
D. Circular DNA and no nucleus
19.
The nucleolus is primarily associated with:
A. ATP production
B. Formation of ribosomal subunits
C. Photosynthesis
D. Lipid storage
20.
The functional segments of DNA that carry genetic information are called:
A. Cristae
B. Genes
C. Vesicles
D. Ribosomes
21.
Which organelle is directly responsible for protein synthesis?
A. Ribosome
B. Lysosome
C. Vacuole
D. Golgi apparatus
22.
Rough endoplasmic reticulum appears rough because:
A. Its membrane is folded.
B. Ribosomes are attached to its surface.
C. It contains DNA.
D. It contains chlorophyll.
23.
Which organelle is mainly associated with lipid synthesis and storage?
A. Rough ER
B. Smooth ER
C. Ribosome
D. Nucleus
24.
The Golgi apparatus mainly:
A. Produces ATP.
B. Modifies, sorts and packages proteins and/or lipids.
C. Stores DNA.
D. Performs photosynthesis.
25.
Lysosomes contain:
A. Chlorophyll
B. Digestive enzymes
C. Chromosomes
D. Cellulose
26.
The folds of the inner mitochondrial membrane are called:
A. Stroma
B. Cristae
C. Vesicles
D. Cisternae
27.
The main energy currency of the cell mentioned in the chapter is:
A. DNA
B. ATP
C. RNA
D. Cellulose
28.
What is the importance of cristae?
A. They store DNA.
B. They increase the surface area of the inner mitochondrial membrane.
C. They produce cellulose.
D. They store cell sap.
29.
Photosynthesis takes place in:
A. Mitochondria
B. Chloroplasts
C. Lysosomes
D. Golgi apparatus
30.
The green pigment that absorbs sunlight in chloroplasts is:
A. Cellulose
B. Chlorophyll
C. Haemoglobin
D. ATP
31.
Plastids containing pigments other than chlorophyll are called:
A. Leucoplasts
B. Chromoplasts
C. Ribosomes
D. Lysosomes
32.
Leucoplasts are mainly associated with:
A. Colour production
B. Food storage
C. Cellular respiration
D. Protein synthesis
33.
The fluid inside a mature plant-cell vacuole is called:
A. Stroma
B. Cell sap
C. Cytosol
D. Plasma
34.
Why does a plant wilt when it lacks sufficient water?
A. Chloroplasts disappear.
B. Vacuoles lose water, reducing cell firmness.
C. Cell walls dissolve.
D. The nucleus leaves the cell.
35.
Mitochondria and plastids are unusual among cell organelles because they:
A. Have no membranes.
B. Possess their own DNA and ribosomes.
C. Are found only in bacteria.
D. Contain no proteins.
36.
Mitosis normally produces:
A. Four genetically different cells
B. Two genetically identical daughter cells
C. Two gametes
D. Four cells with half the chromosome number
37.
Meiosis results in:
A. Two daughter cells with the full chromosome number
B. Four daughter cells with half the chromosome number
C. One daughter cell
D. Four identical body cells
38.
Which process is especially important for sexual reproduction and genetic diversity?
A. Mitosis
B. Meiosis
C. Diffusion
D. Osmosis
39.
Which statement is part of classical Cell Theory?
A. Only plants are made of cells.
B. Cells arise spontaneously.
C. New cells arise from pre-existing cells.
D. Viruses are cellular organisms.
40.
Which scientist is associated with the idea that new cells arise from pre-existing cells?
A. Robert Hooke
B. Rudolf Virchow
C. Camillo Golgi
D. J. Craig Venter
SECTION B — ASSERTION & REASON
41.
Assertion: A potato piece placed in plain water generally gains weight.
Reason: Water can move through a selectively permeable membrane by osmosis.
42.
Assertion: Plant cells generally retain their shape better than animal cells in concentrated solutions.
Reason: Plant cells have a rigid cell wall.
43.
Assertion: Rough ER is associated with protein synthesis.
Reason: Ribosomes are attached to the surface of rough ER.
44.
Assertion: Mitochondria are often called the powerhouse of the cell.
Reason: Cellular respiration releases energy that is stored in ATP.
45.
Assertion: Bacteria are classified as prokaryotes.
Reason: They lack a well-defined membrane-bound nucleus.
46.
Assertion: Meiosis produces four daughter cells.
Reason: The parent cell undergoes two successive divisions.
47.
Assertion: Cancer cells may form tumours.
Reason: Cancer cells can lose normal control over cell division.
48.
Assertion: All plastids are green.
Reason: Chloroplasts contain chlorophyll.
49.
Assertion: Diffusion always requires a selectively permeable membrane.
Reason: Particles can move from higher concentration to lower concentration without a membrane.
50.
Assertion: Mature human RBCs lack a nucleus.
Reason: This provides more space for haemoglobin and supports oxygen transport.
SECTION C — FILL IN THE BLANKS
51.
The basic structural and functional unit of life is the __________.
52.
Robert Hooke first observed cells in a thin slice of __________.
53.
The ability to distinguish two closely spaced objects as separate is called __________.
54.
One millimetre is equal to __________ micrometres.
55.
The movement of water through a selectively permeable membrane is called __________.
56.
A solution with a higher solute concentration outside the cell is called a __________ solution.
57.
The cell membrane is also known as the __________ membrane.
58.
The plant cell wall is mainly composed of __________.
59.
The jelly-like substance inside the cell is called the __________.
60.
The DNA-containing region of a bacterial cell is called the __________.
61.
The organelle responsible for protein synthesis is the __________.
62.
Ribosomes attached to ER make it appear __________.
63.
The ER without ribosomes is called __________ ER.
64.
The Golgi apparatus modifies, sorts and __________ cellular materials.
65.
The folds of the inner mitochondrial membrane are called __________.
66.
ATP is often described as the cell’s __________ currency.
67.
The green pigment found in chloroplasts is __________.
68.
Colourless plastids involved in food storage are called __________.
69.
The watery fluid inside a mature plant-cell vacuole is called __________.
70.
The process by which new cells arise from pre-existing cells is called cell __________.
SECTION D — TRUE OR FALSE
Write True or False.
71.
All living organisms are made up of one or more cells.
72.
The cell membrane allows every substance to pass through freely.
73.
Osmosis involves the movement of water through a selectively permeable membrane.
74.
Animal cells have a rigid cellulose cell wall.
75.
Bacteria are prokaryotic organisms.
76.
Eukaryotic cells have a membrane-bound nucleus.
77.
Ribosomes are sites of protein synthesis.
78.
Smooth ER has ribosomes attached to its surface.
79.
Mitochondria contain their own DNA and ribosomes.
80.
All plastids contain chlorophyll.
81.
Mitosis normally produces four daughter cells.
82.
Meiosis involves two successive divisions.
83.
Cancer cells may divide uncontrollably.
84.
Animal cells generally possess a rigid cellulose cell wall.
85.
Classical Cell Theory states that new cells arise from pre-existing cells.
SECTION E — MATCH THE FOLLOWING
86.
| Column A | Column B |
|---|---|
| 1. Ribosome | a. Photosynthesis |
| 2. Mitochondrion | b. Protein synthesis |
| 3. Chloroplast | c. Cellular respiration |
| 4. Lysosome | d. Breakdown of unwanted materials |
87.
| Column A | Column B |
|---|---|
| 1. RER | a. Food storage |
| 2. SER | b. Protein synthesis |
| 3. Golgi apparatus | c. Lipid synthesis |
| 4. Leucoplast | d. Modification and packaging |
88.
| Column A | Column B |
|---|---|
| 1. Prokaryotic cell | a. Four daughter cells |
| 2. Mitosis | b. Nucleoid |
| 3. Meiosis | c. Two genetically identical daughter cells |
| 4. Eukaryotic cell | d. Membrane-bound nucleus |
SECTION F — VERY SHORT ANSWER
89.
Why are microscopes necessary for studying most cells?
90.
What is the main function of the cell membrane?
91.
What happens to a plant cell when it is placed in a concentrated sugar solution?
92.
What is a nucleoid?
93.
What is the main function of ribosomes?
94.
Why is ATP important to cells?
95.
What is the function of cristae?
96.
What is the main function of chloroplasts?
97.
What are chromoplasts?
98.
Why are vacuoles important in mature plant cells?
SECTION G — SHORT ANSWER QUESTIONS
99.
Differentiate between diffusion and osmosis.
100.
Why does a potato piece placed in concentrated salt solution lose weight?
101.
Why should potato pieces used in an osmosis experiment be approximately equal in size?
102.
Differentiate between prokaryotic and eukaryotic cells.
103.
Why is the cell membrane called selectively permeable?
104.
Differentiate between rough ER and smooth ER on the basis of structure.
105.
Differentiate between the functions of RER and SER.
106.
Explain how the Golgi apparatus works with the ER.
107.
Why are mitochondria and plastids considered unusual organelles?
108.
Why do mature human RBCs lack a nucleus?
109.
Why is mitosis important for growth and repair?
110.
Why does meiosis contribute to variation?
SECTION H — COMPETENCY-BASED QUESTIONS
111.
A student places two similar potato pieces in two beakers. One contains plain water and the other contains concentrated salt solution. After some time, one becomes swollen while the other becomes smaller.
a) Name the process involved.
b) Which potato piece gains water?
c) Why does the other piece lose water?
112.
A cell has a cell wall, chloroplasts, a large vacuole and a well-defined nucleus.
a) Is it prokaryotic or eukaryotic?
b) Is it most likely a plant or animal cell?
c) Give two reasons for your conclusion.
113.
A cell contains DNA in a nucleoid region but has no membrane-bound nucleus.
a) Identify the type of cell.
b) State one other characteristic of this type of cell.
114.
A pancreatic cell produces and secretes large quantities of proteins.
Which organelles would be especially important in this process? Explain the sequence of their involvement.
115.
Suppose a cell suddenly loses most of its mitochondria.
Predict two major consequences.
116.
A plant is kept without sufficient water for a prolonged period.
Explain how changes inside its cells can lead to wilting.
117.
A scientist observes a cell containing chloroplasts but no well-defined nucleus.
Is this observation consistent with the classification described in the chapter? Explain.
118.
A cell contains an extensive membrane network covered with many small particles.
Identify the structure and explain its likely function.
SECTION I — CASE-BASED QUESTIONS
Case Study 1 — Osmosis
A student takes two similar pieces of potato. One is placed in plain water and the other in a concentrated salt solution. After about an hour, the first piece is swollen while the second has shrunk.
119.
What process explains the movement of water?
A. Active transport
B. Osmosis
C. Photosynthesis
D. Cellular respiration
120.
In which direction does water move in the potato placed in concentrated salt solution?
121.
Why does the potato placed in plain water swell?
122.
What property of the cell membrane is essential for this process?
Case Study 2 — A Cell Factory
A researcher studies a cell that produces large quantities of proteins, processes them and eventually sends them outside the cell.
123.
Which structure is the initial site of protein synthesis?
124.
Which type of ER would be particularly important?
125.
Which organelle modifies and packages the proteins?
126.
Why is this an example of coordinated activity among cell organelles?
Case Study 3 — Cell Division
A wound gradually heals because cells replace cells that have been damaged or lost.
127.
Which type of cell division is primarily associated with normal growth and repair?
A. Meiosis
B. Mitosis
C. Fertilisation
D. Osmosis
128.
How many daughter cells normally result from mitosis?
129.
How are these daughter cells genetically related to the parent cell?
130.
Why would meiosis be unsuitable for ordinary replacement of skin cells?
SECTION J — HIGHER-ORDER THINKING
131.
A student says, “A larger image always means a better microscope.” Do you agree? Explain.
132.
Why can the internal contents of a plant cell shrink when placed in a concentrated solution while the outer shape is relatively maintained?
133.
Why can animal cells generally change shape more readily than plant cells?
134.
Why does a cell need different organelles instead of one organelle performing every function?
135.
Why must meiosis reduce the chromosome number before fertilisation?
136.
What would happen to a plant’s ability to produce food if its chloroplasts were severely damaged?
137.
Why can uncontrolled cell division be harmful to an organism?
138.
Why is the statement “all cells are identical” incorrect?
SECTION K — DIAGRAM / IDENTIFICATION QUESTIONS
139.
A diagram shows a cell with:
- a rigid outer layer,
- a cell membrane,
- chloroplasts,
- a large central vacuole,
- and a nucleus.
Identify the cell type.
140.
A diagram shows a cell with:
- no membrane-bound nucleus,
- a nucleoid,
- cell membrane,
- cell wall,
- and ribosomes.
Identify the type of cell.
141.
A cell diagram contains an organelle with an outer membrane and a highly folded inner membrane.
Identify the organelle and name the folds.
142.
A diagram shows flattened sacs arranged in stacks with vesicles budding from them.
Identify the organelle.
143.
A diagram shows a network of membranes covered with small dots.
What do the network and dots represent?
144.
A diagram shows a large compartment inside a mature plant cell filled with watery fluid.
Identify it and name its contents.
SECTION L — NUMERICAL / DATA-BASED QUESTIONS
145.
A microscope field of view has a diameter of 4 mm. Convert this diameter into micrometres.
146.
A field of view has a diameter of 5000 µm. Twenty-five onion cells fit across its diameter. Estimate the average diameter of one cell.
147.
An eyepiece has a magnification of 10X and an objective has a magnification of 20X. Calculate the total magnification.
148.
A student observes 20 cells across a field of view measuring 4000 µm. Estimate the average size of one cell.
SECTION M — INTEGRATED CONCEPT QUESTIONS
149.
Explain how the structure of the cell membrane supports its function.
150.
Compare mitochondria and chloroplasts under these headings:
a) Membranes
b) Genetic material
c) Main function
151.
Explain how the nucleus helps maintain continuity of life from one generation of cells to the next.
152.
Why can a cell be compared with a tiny factory?
153.
How do Cell Theory and cell division complement each other?
SECTION N — CHALLENGE QUESTIONS
154.
A student claims: “Since chloroplasts capture light energy, plants do not need mitochondria.” Is this correct? Explain.
155.
A cell has a membrane-bound nucleus but lacks chloroplasts. Can it still be a plant cell? Explain based on the chapter.
156.
Why would removing the cell wall from a plant cell affect its ability to withstand environmental stresses?
157.
If the Golgi apparatus stopped functioning, which cellular processes would be directly affected?
158.
Why is controlled cell division important for an organism?
159.
How does programmed cell death contribute to normal development?
160.
The chapter discusses research in which synthetic DNA was introduced into a cell whose original DNA had been removed, after which the cell grew and divided according to the inserted instructions. What major conclusion does this support?
SECTION O — ONE-WORD / ONE-TERM REVISION
161.
Name the scientist who first observed cells in cork.
162.
What is the DNA-containing region of a bacterial cell called?
163.
What is the site of protein synthesis?
164.
Which organelle is commonly called the powerhouse of the cell?
165.
Which plastid is green?
166.
Which plastids contain pigments responsible for many flower and fruit colours?
167.
Which plastids are mainly involved in food storage?
168.
Which organelle contains digestive enzymes?
169.
Which organelle modifies and packages cellular materials?
170.
Which type of cell division produces two genetically identical daughter cells?
171.
Which type of division produces four cells with half the chromosome number?
172.
What is the movement of water through a selectively permeable membrane called?
173.
What is genetically regulated cell destruction called?
174.
What property allows a mature plant cell under suitable conditions to potentially develop into an entire plant?
175.
What is the process in which many animal cells stop dividing after making contact with neighbouring cells called?
Cell: The Building Block of Life — Answer Key
Section A — MCQs
- B
- C
- B
- C
- B
- B
- B
- B
- B
- C
- B
- B
- C
- B
- C
- C
- B
- B
- B
- B
- A
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- B
- C
- B
Section B — Assertion & Reason
- A
- A
- A
- A
- A
- A
- A
- D
- D
- A
Section C — Fill in the Blanks
- Cell
- Cork
- Resolution
- 1000
- Osmosis
- Hypertonic
- Plasma
- Cellulose
- Cytoplasm
- Nucleoid
- Ribosome
- Rough
- Smooth
- Packages
- Cristae
- Energy
- Chlorophyll
- Leucoplasts
- Cell sap
- Division
Section D — True or False
- True
- False
- True
- False
- True
- True
- True
- False
- True
- False
- False
- True
- True
- False
- True
Section E — Match the Following
86.
1 – b
2 – c
3 – a
4 – d
87.
1 – b
2 – c
3 – d
4 – a
88.
1 – b
2 – c
3 – a
4 – d
Section F — Very Short Answers
89.
Most cells are too small to be clearly resolved by the unaided human eye, so microscopes are needed to observe them.
90.
The cell membrane encloses the cell and selectively regulates the movement of substances into and out of it.
91.
Water moves out of the plant cell by osmosis, causing the cell contents to shrink.
92.
The nucleoid is the region of a prokaryotic cell where its genetic material is located.
93.
Ribosomes are responsible for protein synthesis.
94.
ATP stores and supplies energy needed for various cellular activities.
95.
Cristae increase the surface area of the inner mitochondrial membrane, providing more area for cellular reactions.
96.
Chloroplasts are the sites of photosynthesis in plant cells.
97.
Chromoplasts are plastids containing pigments other than chlorophyll that contribute to the colour of flowers and fruits.
98.
Vacuoles store substances and help maintain internal pressure, keeping mature plant cells firm.
Section G — Short Answers
99.
Diffusion is the movement of particles from a region of higher concentration to lower concentration.
Osmosis is the movement of water through a selectively permeable membrane.
100.
The concentrated salt solution has a lower water concentration than the potato cells. Water therefore moves out of the cells by osmosis, causing the potato piece to lose mass.
101.
Approximately equal-sized pieces provide similar starting conditions, making the comparison between the different solutions more reliable.
102.
Prokaryotic cells: Lack a well-defined membrane-bound nucleus and membrane-bound organelles.
Eukaryotic cells: Have a well-defined membrane-bound nucleus and membrane-bound organelles.
103.
It is called selectively permeable because it permits some substances to cross while restricting others.
104.
RER: Has ribosomes attached to its surface.
SER: Does not have ribosomes attached to its surface.
105.
RER is mainly involved in protein synthesis, while SER is associated mainly with lipid synthesis and storage.
106.
The ER produces or processes materials that can be transported to the Golgi apparatus. The Golgi then modifies, sorts and packages these materials for transport or secretion.
107.
Mitochondria and plastids have their own DNA and ribosomes, unlike most other cell organelles.
108.
Mature human RBCs lack a nucleus, providing more space for haemoglobin and supporting oxygen transport.
109.
Mitosis increases cell number and produces genetically identical daughter cells, making it important for growth, repair and maintenance.
110.
Meiosis produces gametes and contributes to genetic diversity, which results in offspring that are not genetically identical to their parents.
Section H — Competency-Based Answers
111.
a) Osmosis
b) The potato in plain water
c) Water moves out of the potato cells into the concentrated salt solution because of the difference in water concentration.
112.
a) Eukaryotic
b) Plant cell
c) It has a well-defined nucleus, cell wall, chloroplasts and a large vacuole.
113.
a) Prokaryotic cell
b) It lacks membrane-bound organelles.
114.
Ribosomes synthesize the proteins, particularly on the rough ER. The proteins are then processed and transported to the Golgi apparatus, which modifies, sorts and packages them for secretion.
115.
ATP production through cellular respiration would be greatly reduced. Consequently, many energy-dependent cellular activities would be affected.
116.
Water loss causes the vacuoles to lose water and internal pressure. The cells become less firm, causing the plant to wilt.
117.
No. A chloroplast is a membrane-bound organelle characteristic of eukaryotic plant cells, which have a well-defined nucleus.
118.
The structure is the rough endoplasmic reticulum, and the small particles are ribosomes. It is involved mainly in protein synthesis and processing.
Section I — Case-Based Answers
Case Study 1 — Osmosis
119.
B. Osmosis
120.
Water moves out of the potato cells into the concentrated salt solution.
121.
Water enters the potato cells from the more dilute external medium by osmosis.
122.
Selective permeability of the cell membrane.
Case Study 2 — A Cell Factory
123.
Ribosomes
124.
Rough endoplasmic reticulum (RER)
125.
Golgi apparatus
126.
Different organelles perform different stages of protein production, processing, packaging and transport, working together as a coordinated system.
Case Study 3 — Cell Division
127.
B. Mitosis
128.
Two daughter cells
129.
They are genetically identical to the parent cell under normal mitotic division.
130.
Meiosis produces cells with half the chromosome number and is associated with gamete formation and sexual reproduction rather than ordinary tissue repair.
Section J — Higher-Order Thinking
131.
No. A larger image does not necessarily mean a better microscope. Resolution and contrast are also important because they determine how clearly structures can be distinguished.
132.
Water leaves the cell by osmosis, causing the cell contents to shrink. The rigid cell wall helps maintain the cell’s outer shape.
133.
Animal cells lack the rigid cell wall present in plant cells, allowing them greater flexibility in shape.
134.
Different organelles are specialised for different functions. This division of labour allows cellular activities to occur efficiently and in a coordinated manner.
135.
Meiosis produces gametes containing half the chromosome number. During fertilisation, the chromosome number is restored when two gametes combine.
136.
Damage to chloroplasts would reduce the plant’s ability to carry out photosynthesis and therefore reduce its ability to produce food.
137.
Uncontrolled cell division can result in abnormal accumulation of cells and may lead to tumour formation.
138.
Cells share certain basic features but differ in structure and function. Different cell types are specialised for different jobs.
Section K — Diagram / Identification
139.
Plant cell
140.
Prokaryotic/bacterial cell
141.
Mitochondrion — folds are called cristae
142.
Golgi apparatus
143.
Rough endoplasmic reticulum and ribosomes
144.
Vacuole — contains cell sap
Section L — Numerical / Data-Based
145.
4000 µm
146.
200 µm
147.
200X
148.
200 µm
Section M — Integrated Concepts
149.
The cell membrane consists of a lipid bilayer with water-attracting heads facing outward and water-repelling tails facing inward, along with embedded proteins. This structure allows selective movement of substances and helps maintain the cell’s internal environment.
150.
| Feature | Mitochondria | Chloroplasts |
|---|---|---|
| Membranes | Double membrane | Double membrane |
| Genetic material | Own DNA and ribosomes | Own DNA and ribosomes |
| Main function | Cellular respiration and energy release | Photosynthesis |
151.
The nucleus contains chromosomes made of DNA and associated proteins. DNA carries genetic information, which is passed to daughter cells during cell division.
152.
A cell can be compared with a factory because different organelles perform specialised functions such as energy production, protein synthesis, storage, modification, packaging and waste breakdown.
153.
Cell Theory states that new cells arise from pre-existing cells. Cell division explains how existing cells produce new cells, supporting growth, repair and reproduction.
Section N — Challenge Answers
154.
The statement is incorrect. Chloroplasts carry out photosynthesis, whereas mitochondria carry out cellular respiration and help make usable energy available as ATP. They perform different functions.
155.
Yes. A plant cell may lack chloroplasts if it is a specialised cell that does not carry out photosynthesis. The presence or absence of chloroplasts alone does not determine whether every individual plant cell is a plant cell.
156.
The cell wall provides rigidity, maintains cell shape and helps support the plant against environmental stresses. Removing it would therefore reduce this structural support.
157.
Modification, sorting and packaging of proteins and lipids would be affected. Transport and secretion of these materials and formation of lysosomes would also be affected.
158.
Controlled cell division ensures that cells are produced when required for growth, repair and maintenance. Loss of control can cause abnormal cell proliferation.
159.
Programmed cell death removes cells that are no longer required. During development, this helps shape tissues and organs.
160.
It supports the conclusion that DNA contains instructions that control the structure and activities of a cell. It does not, however, demonstrate that a completely new cell can be created from non-living material.
Section O — One-Word / One-Term Answers
161.
Robert Hooke
162.
Nucleoid
163.
Ribosome
164.
Mitochondrion
165.
Chloroplast
166.
Chromoplasts
167.
Leucoplasts
168.
Lysosome
169.
Golgi apparatus
170.
Mitosis
171.
Meiosis
172.
Osmosis
173.
Programmed Cell Death (PCD)
174.
Totipotency
175.
Contact inhibition
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